The Washington University Program in Principles of Pulmonary Research provides multidisciplinary training for predoctoral and postdoctoral scholars committed to a career in respiratory research. The postdoctoral portion of the Program enables MD and MD/PhD physicians who are training in pulmonary and critical care medicine to learn state-of-the-art scientific research in concert with PhD trainees from a basic science background. The predoctoral portion of the Program engages students in the MD/PhD and PhD graduate division to work in close connection with the same respiratory research curriculum. The proposal remains at seven postdoctoral and five predoctoral trainees with 2-3 years of support before transitioning to additional career development awards. The aim of the Program is to promote the career development of trainees so they will enter academic pulmonary medicine with the skills needed to study problems relevant to respiratory diseases. The Program is closely monitored through a Director and four Committees (Internal Advisory, External Advisory, Review, and Diversity Recruitment) and relies on 25 senior mentors, 11 junior mentors, and 15 support faculty distributed into a coordinated set of three interdisciplinary research tracks, including two basic-translational tracks (Immunology-Host Defense and Epithelial Cell-Matrix Biology) and one clinical-translational track (for further application to human disease). The basic tracks are designed to correspond to the major themes of the pulmonary research program and to coincide with the graduate training program, and the clinical track is aimed at extending these fields to human subject research and the CTSA curriculum. This program structure allows for a broad-based faculty from 13 departments to coordinate and focus research activities and trainee supervision in a collaborative and synergistic process. For all trainee activities within this structure, there is also a carefully constructed mentoring process that includes benchmarks for individual trainee presentation, publication, and grant application. To achieve these goals, all predoctoral and postdoctoral trainees engage in the same research review process that is home-based around a joint Research and Development Conference. This conference is the hub for input from an overall Program Review Committee (that includes the Program Director and his advisors) and a project-specific Advisory Committee (that includes the trainee's mentors, co- mentors, and collaborators). Trainees also receive input via individual lab and group meetings as well as additional research conferences that are set up to coordinate with the research themes of the Program. The research-intense experience is supplemented through graduate coursework to build general skills and specific knowledge of a research field. Together, these mechanisms serve to ensure high-level trainee experiences and performance in previous and present cycles of this longstanding and highly successful Program.